fix(llm): add fetch-models endpoint, fix SQL Lab INSERT (client_id truncation, sync mode, target_column, timestamp normalization)

- Add POST /api/llm/providers/fetch-models route with LLMClient.fetch_models()
- Add target_column to TranslationJob model/schema/service/orchestrator
- Fix SQL Lab execute: truncate client_id to 11 chars (varchar(11))
- Switch SQL Lab to sync mode (runAsync: false) — no Celery workers
- Fix polling: unwrap nested result from Superset query API
- Fix ClickHouse timestamp: normalize float timestamps to YYYY-MM-DD

backend/tests/services/clean_release/test_policy_resolution_service.py

@@ -1,5 +1,4 @@
 # [DEF:TestPolicyResolutionService:Module]
-# @COMPLEXITY: 5
 # @SEMANTICS: clean-release, policy-resolution, trusted-snapshots, contracts
 # @PURPOSE: Verify trusted policy snapshot resolution contract and error guards.
 # @LAYER: Tests
@@ -24,7 +23,6 @@ from src.services.clean_release.repository import CleanReleaseRepository
 
 # [DEF:_config_manager:Function]
 # @RELATION: BINDS_TO -> [TestPolicyResolutionService]
-# @COMPLEXITY: 1
 # @PURPOSE: Build deterministic ConfigManager-like stub for tests.
 # @INVARIANT: Only settings.clean_release.active_policy_id and active_registry_id are populated; any other settings field access raises AttributeError.
 # @PRE: policy_id and registry_id may be None or non-empty strings.